Conventional methods for contacting a rear-passivated solar cell use laser ablation of the silicon wafer. In such methods, a high power laser is fired over the rear surface of the cell, which thermally ablates the deposited passivation layer. This process has several disadvantages. First, laser ablation damage of the silicon underneath the surface lowers the cell efficiency. Second, because the laser must raster over the entire surface area, the process can be time-consuming. Laser ablation is not amenable to producing intricate shapes and high resolution detail in the rear surface, which can increase efficiency. Moreover, this method is not able to control the depth into the solar cell. This is significant because the final efficiency of the cell can be dependent on the depth of the opened surface, and as a laser ablates more material, this generally results in greater thermal damage to the substrate and a corresponding lower efficiency.
What is thus needed in the art are improved methods of fabricating rear-passivated solar cells that overcome the problems of conventional approaches, such as laser ablation.